Stitch forming mechanism for sewing machines



April 11, 1933. H. F. GRUMAN STITCH FORMING MECHANISM FOR SEWING MACHINES origina 511e@ Jan. 51, 1931 2 snets-sheet l mm. wv Q .um n Nk Cttorneg April 11, 1933. H. F. GRUMAN STITCH FORMING MECHANISM FOR SEWING MACHINES Original Filed Jan. 3l, 1931 2 Sheets-Sheet 2 attorney Patented pr. 11,1933

UNITED [s-'TATES AInstrENT, OFFICE f HORACE r. GRUMAN, oF'S'r. LOUIS, MISSOURI;` V.eIsSIeNoa rro LEWIS INVISIBLE s'rI'rcrI MACHINE COMPA'NY, 0F ST.

LOUIS, MISSOURI, A CORPORATION OF MAINE StrI'rcII-rom/IINGMECHANISM Non SEWING MACHINES Original application iledvlanuary 31, `193.1, serialNo. 512,661. klvDivided and this application led September This invention :relatesV to lnevi/' and useful improvements in stitch 'fforming mechanisms for sewing machines, 'andvoonstitutes a division of myfco-pending application Serial blo/512,661, filed J an( 31, 1931, for Vsewing machines( Y v f ,y 1

Among'the several obj ects of my invention are to provile a Vstitch forming mechanism which is capableof being readily applied Within a tubular workarm 'of. comparatively small cross sectional area v to Vprm'ride an oscillatory needle shaft which entends longi tudinally of the armand to'which theneedle is fixedfor reciprocatory movementsV in a plane at right angles to the axis ofthe shaft; to provide a l-motion threaded looperffor cooperation with the needle; to provide driving connections between the needle, shaft and the looper for imparting loop entering and loop shedding movements tothe looper; t0 than 4the needle shaft provide meansothen for imparting needle avoiding movements to the looper, and to provide such. a mechanism which is composed of `but Yfewparts .and is therefore simple in construction and cheap tomanufacture.V

` With these and other objects in view which will more:fully appear, the natureof the invention will be more clearly following the description; the appended claims, and the Several viewsi illustrated in the accompanying drawings., l.:

In the drawingsz-` 7 i Figure 1 is a top'plan view'ofa work arm showing the "application of my invention therein,V y Y Figure 2 is a detail; vertical sectional viewVY showing the driving `connections for the needle shaft and thelooper,V1 f' Figure' 3 is a perspective" 0I are guard plate which reta-insthelooper carrierfin .its

bearing, and

AFigure 7 is., detail horizontal s ec'tional understood 'by seriai No. 563,342.

view showing the means for oscillating the looper carrier from the needle shaft. y

Like reference numerals designate corresponding parts throughout the several figures ofthe drawings.

14,15 and an' intermediate bearing 16, the rear andintermediate bearingsbeing formedv 'in fa post 17 which is. integral with the bracketll and extends upwardly into the arm l.10. 'Dowel pins 18, 18 which act as 'centering pins also connect the bottom 12 of the arm and the bracket 11. g

' Journaled 'n the bearings above described is an oscillatory needle shaft 19 which of course extends longitudinally of the 'Work l arm. The shaft is retained against longitudinal movements relative to the bracket 11` by means of a collar20 which engages the front bearingll and by the hub 2 1 of a needle arm 22 which is clamped to the shaft on that Side ofthe bearing 16 opposite the bearing l5. I The needle arm22 extends'rad ially from the'shaft and thence rearwardly past thev right hand side of the bearing post 17, and' attached to the free end ofthe needle arm is acurved needle 23 which oscillates in Y an arcuate pathextending above the shaft ,19 and in a` Vertical plane at right angles" to the longitudinal axis of said shaft. Thus the needle 23 oscillates wholly within the connesof thecross sectional area ofthe work j farm 10. iew-of a bracket on which the looper mechanism is mounted, Figure 4 is a perspective'view ofthe looper 'Cooperfating with the needle 23 t0 form a lineof Grover 4and Baker stitches is a .4- mo-- tion threaded looper 24 which isV rigidly connected, preferably integrally, ,to a looper holder 25 havngbeveied Side edges 26, 2e, A, looper carrier 27's mounted for oscillatory movements'i'n a Yrecessedbearing 28 formed in the post 17, the longitudinal axis of the Y "bearing 28V beingf'n ahorizontal plane and a plane at rightv angles to the longitudinal toward'the operator or in other words, in a direction opposite the free end ofthe work sarm. When the carrier 27 is oscillated the looper 24 is 'given its loopV taking and loop shedding movements or in other words its forwardandbackward travel, and when the looper holder 25 is reciprocated insaid car- 4rier the looper is given its needle avoiding movements which, as is well'known in the art, is necessary to insure the fiat setting of a looper thread inthe stitches being formed. A gua-rd plate which is removably attached to thev left hand face of the bearing post 17 projects slightly beyond the bearing28 to retain the'looper carrier 27 in said bearing.

l In order to oscillate the looper carrier 27 and thereby impart loop entering and loop shedding movements to the looper 24, I have fixedly mounted a driving bevel gear 31 on the rear end of the needle shaft 19 and have y Y' protected said gear from lint and the like by Alocating said gear in a recess 32 formed in the bearing post 17. The gear 31'is in constant mesh with a driven'gear 33 fixed tothe inner face of the looper carrier 27 to oscil- ,late the latter upon voscillation of the needle shaft 19. The gear coupling 31, 33 is a l-to-l coupling and consequently the looper travel mechanism is timed with the needle travel mechanism whereby the loop taking orloop y, entering movement of the looper begins simultaneously with Vthe retractile movement of the needle, and the loop shedding movement of the looper begins simultaneously with thev penetrating or forward stroke of lfthe needle.

In order to impart needle y.avoiding movements vto the looper 24, I have provided a vertical link 34 having its lower end pivot-- ally connected to the front end of a lever 35 which extends longitudinally within the work v arm 10 on the left side of the needle sha-ft 19, and is fulcrumed intermediate its ends on a horizontal pivot screw 36 mounted on the 'bracket 11. The rear end of the lever 35 is ,i provided with an upstanding arm 37 having substantially horizontal arms 38, 39 and forming therebetween a slot 40.. Y slide block V41 is fulcrumed on a pivot screw 42 fixed to the looper holder-25, and this block 41 isy Y mountedl in the slot 4() for sliding movements relative tothe arms 38, 39. Thus when the vertical link 34 is oscillated lengthwise, the

25 and above the I movable in with an oscillatory shaft; ltending arm fixed to said lever-35 will be correspondingly oscillated, and therefore the looper holder 25 will be raised and lowered along the groove or guiding channel 29 of the looper carrier 27 and thereby imparting needle avoiding inovel .ments to the looper. The parts are timed so 'that the needle avoiding movements of the looper lwill be imparted at opposite ends of the'loopertravel.V The looper in its forwardV with an oscillatory shaft; of a radially eX-""` tending arm xed to said shaft; a curved needle fixed to said arm for oscillation in a plane at'right angles to the longitudinal axisA dependent of the shaft and cooperating with l" the needle, driving connections between vthe shaft andthe looper for imparting loop-tak- Ving and loop-shedding movements to the loop- Y of the shaft; a 4-motion threaded looper Yiner, and means separate from the shaft for imparting needle-avoiding movements to the looper.

2. In a sewing shaft; of a radially extending arm fixed to said shaft; va curved needlefxed to said arm for oscillation in a plane at right angles to the longitudinal axis of the shaft; a 4-motion threaded looper independent of the shaft and cooperating with the needle, driving connectionsr between the.. shaft and the loopervfor imparting loop-tak-fy Aing and loop-shedding movements 'to the looper including an oscillatory looper carrier a plane at right angles tothe path of needle tween the shaft and the carrier, and means separate from the shaft for imparting needleavoiding movements to the looper. i` i movement and a gear coupling lne-...n0

machine, the combination l lwith anv oscillatory 3. In a `sewing machine, the combinaton i of a radially exs,f shaft; `a curved" needle fixed to saidrarm for oscillation in a plane at right angles to the longitudinal axis of the shaft; an loscillatory looper carrier movable in a plane at right angles to the path of needle movement, a looper holder mounted in the carrier for bodily movements therewith and for radial reciprocatory movements relative thereto, a threaded looper xedto said holder, driving connections between the shaft Vand carrier'for oscillating the latter to impart loop-taking and loop-shedding movementsto the looper, andmeans connected to vthe looper holder for imparting needle avoiding movements to the looper. f 4. In a sewing machine, the combination with an oscillatory shaft; of a radially extending arm fixed to said shaft; a curved needle fixed to said arm for oscillation in a lane at right angles to the longitudinal axis of the shaft; an oscillatory looper carrier movable in a plane at right angles to the path of needle movement, said carrier being provided with a radially disposed guiding channel, a looper holder slidably mounted in the channel of the carrier for bodily kmovements with the carrier `and for radial reciprocatory movements relative thereto, a threaded looper fixed to said holder, driving connections between the shaft and carrier for oscillating the latter to impart loop-taking and loopshedding movements to the looper, and means connected to the looper holder for imparting needle-avoiding movements'to the looper.

5. In a sewing machine, the combination 2o with an oscillatory shaft; of a radially extending arm fixed to said shaft; a curved needle fixed to said arm for` oscillation in a plane at right angles to the longitudinal axis of the shaft; a i-motion threaded looper cooperating with the needle; and means for operating said looper comprising a fixed casing having a circular bearing, a looper carrier mounted in the bearing of the casing for oscillations about an axis parallel withthe- 3o plane of needle reciprocations, said carrier being provided with a radially extending guiding channel, a looper holder mounted in said guiding channel for bodily movements with the carrier and for radial reciprocatory movements relative thereto,driving connections between the shaft and the looper for imparting loop-taking and loop-shedding movements to the looper, and means separate from the shaft for imparting needle-avoiding movements to the looper.

In testimony whereof I aiix my signature.

HORACE F. GRUMAN 

